1. Field of the Invention
The present invention relates to pacer housings and more particularly to those parts of the housing intended for connection to the electrode leads.
2. Description of the Prior Art
Implantable pacers normally comprise a pacer housing (also called can) containing electronic circuitry and a unit for electric power as well as different electrodes which are connected to the interior parts in the pacer housing and which are to be implanted in or in the vicinity of the heart. The electrodes are connected to the pacer by means of leads. The internal parts of the pacers have to be well protected against the internal environment, especially the body fluids in the body for a long period of time, which places strict requirements on all entries into the interior of the can and especially on the connections of the leads to the housing. At the same time it should be possible to disconnect the pacer from the implanted leads for replacement or servicing of the pacer. The connective parts of the pacer and the leads have largely been standardized so as to encompass a relatively deep female socket comprising a number of contact surfaces whereas the leads are provided with a male part comprising one or several corresponding peripheral, generally circular contact surfaces.
When a pacemaker is being implanted, it is important that the physician is able to ascertain that the proximal ends of the electrode leads are fully inserted so as to ensure that respective contact surfaces fully are in engagement. It furthermore is important that the male part of the leads can be securely locked in the female part socket in the pacer housing when all connections have been made.
At present these problems in most cases are addressed by making the connective part of the pacer housing containing the female socket of a transparent material, normally epoxy resin, which is molded onto the housing and onto contacts extending outwardly from the housing. The male part of the leads is normally locked by means of set screws, although other fastening means are known. By these means the physician is able to determine visually whether the male contact part of the lead has been fully inserted into the female socket before tightening the set screws. The positioning and alignment of the different contact surfaces and of the fastening means or metallic threads for the set screws prior to the moulding of the connective part is however very complicated and the delay in the manufacturing process incurred by the curing of the epoxy resin is considerable.
It would thus be desirable if the molding procedure could be dispensed with.